首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3133篇
  免费   227篇
  国内免费   58篇
耳鼻咽喉   16篇
儿科学   28篇
妇产科学   16篇
基础医学   268篇
口腔科学   72篇
临床医学   451篇
内科学   289篇
皮肤病学   37篇
神经病学   241篇
特种医学   102篇
外科学   175篇
综合类   388篇
预防医学   548篇
眼科学   45篇
药学   434篇
  12篇
中国医学   151篇
肿瘤学   145篇
  2024年   6篇
  2023年   53篇
  2022年   95篇
  2021年   104篇
  2020年   113篇
  2019年   110篇
  2018年   98篇
  2017年   120篇
  2016年   113篇
  2015年   135篇
  2014年   242篇
  2013年   297篇
  2012年   196篇
  2011年   198篇
  2010年   152篇
  2009年   149篇
  2008年   147篇
  2007年   151篇
  2006年   136篇
  2005年   111篇
  2004年   92篇
  2003年   63篇
  2002年   64篇
  2001年   58篇
  2000年   39篇
  1999年   31篇
  1998年   29篇
  1997年   34篇
  1996年   27篇
  1995年   26篇
  1994年   27篇
  1993年   20篇
  1992年   14篇
  1991年   13篇
  1990年   11篇
  1989年   16篇
  1988年   16篇
  1987年   11篇
  1986年   10篇
  1985年   18篇
  1984年   27篇
  1983年   3篇
  1982年   5篇
  1981年   6篇
  1980年   11篇
  1978年   5篇
  1975年   4篇
  1974年   4篇
  1972年   2篇
  1968年   2篇
排序方式: 共有3418条查询结果,搜索用时 15 毫秒
71.
72.
Coagulation factor VIII (FVIII) is an important glycoprotein co-factor involved in haemostasis, functioning to accelerate activation of factor X by activated factor IX. Insertion of expression vectors containing the full-length cDNA sequence of human FVIII into mammalian cell lines results in the production of recombinant factor VIII (rFVIII), typically referred to as 'full-length' rFVIII (FLrFVIII). Both FLrFVIII and plasma-derived FVIII exist primarily as heterodimeric proteins, consisting of a heterogenous light and heavy chain. The objectives of this study were to compare the structural heterogeneity of high-purity FVIII preparations and further define the term 'full length' as it refers to rFVIII protein structure. Five commercially available FVIII concentrates were characterized based on SDS-PAGE, N-terminal sequencing, and peptide and domain mapping coupled to mass spectrometry. The major heavy chain species identified in FLrFVIII included various B-domain-truncated forms of FVIII, with the predominant species terminating at Arg(1313). This study demonstrates that the use of full-sequence FVIII cDNA for the production of rFVIII does not result in a homogeneous FLrFVIII protein product. Rather, commercially available FLrFVIII represents a heterogenous mixture of various B-domain-truncated forms of the molecule, with no evidence of a contiguous, intact B-domain.  相似文献   
73.
The goal of this study was to compare data for women with bulimia nervosa and for a healthy control group both in Japan and Germany. These data were obtained using the Eating Disorder Inventory (EDI‐2). In Germany, EDI‐2 data and BMI values were collected from 102 nurses in training, 57 female medical students, and 29 patients with bulimia nervosa. In Japan, data were gathered from 243 female ‘short college’ students and 20 patients with bulimia nervosa. The Japanese non‐clinical control group showed significantly higher values on nearly all EDI scales than the German control group. They had a markedly higher drive for thinness, though their BMI values were lower. When the German and the Japanese bulimia nervosa patients were compared, the Japanese patients also showed higher values than their German counterparts on three EDI scales, but these differences were negligible. It is suggested that sociocultural factors in Japan, in particular a significant dependency on social norms, may contribute to the high EDI values. Copyright © 2005 John Wiley & Sons, Ltd and Eating Disorders Association.  相似文献   
74.
75.
Many factors influence the final oocyte maturation, fertilisation, and early embryo development, and there are both similarities and differences between species. When comparing the advancement of assisted reproductive technologies (ARTs), the development in the bovine species is not far behind the medical front, with around one million in vitro-produced bovine embryos each year. This rate of progress is not seen in the other domestic species. This review aims to give an overview of the development and specific difficulties of in vitro embryo production in various domestic animal species, with the main focus on cows, pigs, and cats. In production animals, the aim of ARTs is commonly to increase the genetic progress, not to treat reproductive failure. The ARTs are also used for preservation of genetic diversity for the future. However, specifically for oocyte maturation, fertilisation, and early embryonic development, domestic mammals such as the cow and pig can be used as models for humans. This is particularly attractive from an animal welfare point of view since bovine and porcine oocytes are available in large numbers from discarded slaughterhouse material, thereby decreasing the need for research animals. Both for researchers on the animal and human medical fronts, we aim for the development of in vitro production systems that will produce embryos and offspring that are no different from those conceived and developed in vivo. Species-comparative research and development can provide us with crucial knowledge to achieve this aim and hopefully help us avoid unnecessary problems in the future.  相似文献   
76.
77.
78.
目的 通过分析郴州市一起新冠肺炎聚集性疫情相关病例发病确诊过程,探讨新冠病例早发现、早报告以及病例诊断和隔离观察解除的策略依据。 方法 对该起新冠肺炎聚集性疫情的病例和密切接触者进行现场流行病学调查,描述性分析流行病学史、临床和实验室资料。 结果 利用大数据比对监测,在转送监测对象至集中场所隔离医学观察时发现了新冠肺炎确诊病例何某华,由此发现一起新冠肺炎家庭聚集性疫情,何某的5名密切接触者中有3人发病确诊(包含1名重症病例),其中重症病例黄某第7次新型冠状病毒核酸检测阳性进而确诊,密切接触者中胡某有流行病学史、血常规白细胞下降和肺炎影像学改变,但是5次咽拭子核酸检测阴性,未确诊。 结论 大数据比对监测对发现传染病有积极作用;早期对有流行病学史人员单独隔离医学观察对防止聚集性疫情发生有重要意义;将2次核酸检测阴性作为新冠肺炎病例的排除标准和将核酸检测阳性作为确诊新冠肺炎病例的必备条件,值得探讨,这都可能放走传染源,导致新冠肺炎传播。  相似文献   
79.
80.

Background

Amoxicillin is an oral semi-synthetic, β-lactam antibiotic used to treat bacterial infections caused by susceptible micro organisms. It is usually prepared in capsule, tablet and powder for oral suspension form. Solid dosage forms for oral administration pose bioavailability problems related to the absorption process The World Health Organization (WHO) has promoted the use of generic brands in order to make the cost of medicines affordable. Generic substitution could be considered when a generic copy of a reference drug contains identical amounts of the same active ingredient in the same dose formulation and route of administration. However, the presences of generic products those are not interchangeable with that of the innovator and/or with each others have been reported.

Objectives

To evaluate and compare the in-vitro dissolution profiles of different generic brands of amoxicillin capsules with the innovator that are available in Ethiopian market.

Methods

Dissolution profiles for nine brands of amoxicillin capsules contained amoxicillin 500 mg which are available in Ethiopian market were determined using a method from the United States Pharmacopoeia (USP, 2009). The obtained dissolution profile data of the eight brands were evaluated and compared with the innovator brand (Amoxil™) using two different statistical methods: the fit factors (f1 & f2) and the dissolution efficiency (D.E.) model. Most generic brands of amoxicillin capsules (62.5% of the tested brands) are not interchangeable with the innovator brand.

Results

The calculated f1 factor for Brand A and Brand G are 10.1 and 1.1 respectively. However, for the rest six brands the f1 factors are greater than 15. The f2 factor for Brand G is 74.1 and for Brand A is 48.5 which is near to 50. Similarly, the f2 factors for the six brands are less than 50 which support the result of the f1 factors for the dissimilarity of these brands with the innovator brand. The mean dissolution efficiencies as well as the 95% confidence intervals are within ±10% only for two brands, Brand F and Brand G.

Conclusions

Most generic brands of amoxicillin capsules (62.5%) are not interchangeable with the innovator brand (Amoxil™).  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号